Aerobrake
Aerobraking is a technique that uses a planet's atmosphere to slow down a ship. Entering Orbit Aerobraking comes with huge advantages if you want to save fuel. If you send a ship towards another planet, it will enter that planet's Sphere of Influence. Without firing the engines, the ship will continue its trajectory until it will escape back into a heliocentric orbit. By sending a ship on a trajectory that intersects the outer layers of an atmosphere, you can slow it down and force it into an orbit. Mars Mars has a rarefied atmosphere. A ship coming from Earth can be slowed down enough to gain orbit if it crosses the Martian atmosphere. In order to do this, try to set the flight path at 5/8 to 6/8 of the height of Martian atmosphere. This will send the ship into an elliptic trajectory, with its apogee inside the Martian sphere of influence and the perigee inside the atmosphere. By repeating the process, you can further lower the apogee or even enter an impact trajectory. By setting the flight path to intersect the Martian atmosphere at 1/2 of its height or lower, the ship will be slowed down enough to land without re-entering space. Warning! If you send the trajectory to intersect with the Martian atmosphere at only 7/8 of its height, the ship will not be slowed significantly. Earth The Earth has a dense atmosphere. Usually, Earth is the final destination for ships returning from other planets. However, someone might want to reuse a ship, refuel it and send somewhere else. In order to do so, a ship must intersect Earth's atmosphere somewhere around 6/8 to 7/8 of the height of the atmosphere. Venus Venus has a very dense atmosphere, which is well-suited for aerobraking. A ship approaching Venus from Earth or Mercury can aerobrake to gain orbit, saving fuel. In order to do this, try to set the flight path to intersect the atmosphere at 7/8 of its height. Below that limit, the atmosphere greatly slows down a ship. Above that limit, it might be possible for a ship to not be slowed enough. Warning! Venus has a high gravity and a dense atmosphere. It is very hard for a ship to fly back through the atmosphere to orbit. If the flight path is set too low, the ship will need to fire its engines to oppose the effects of aerobraking. Fuel consumption might be greater then what would be otherwise needed to enter orbit. The Sun The Sun has a dense atmosphere, which can be used for aerobraking, to gain a lower heliocentric orbit. However, this is very risky and difficult to obtain. Other bodies It is known that both Mercury and the Moon have very rarefied atmospheres, so they cannot be used for aerobraking in any ways, both in the game and in reality. Landing Aerobraking is largely used for landing, because it reduces the speed of a ship down to the point where parachutes can operate safely. Mars Mars, with its rarefied atmosphere, can slow down a ship that is not entering direct orbit. This is why aerobraking can be very useful, first to enter orbit and then to reduce the speed as much as possible. Landing on Mars might require some engine burns and/or the use of many parachutes. Earth Earth's atmosphere can slow down enough any ship that is approaching. If your ship is moving very fast (for example a return mission from Mercury or a future return mission from a gas giant), set your ship to hit the Earth at an angle (close to the poles). Venus Venus has a dense atmosphere, enough to slow down any ship to the point where a parachute is enough. Approach Venus in any angle without fearing the consequences. The Sun The Sun also has a dense atmosphere and can slow down any ship. If you try to land on the Sun, your ship will slow down, reach altitude zero, then will continue to sink slower, forever or until you are too bored to wait. Moving Up The atmosphere slows down any ship passing through. The effect is much stronger if your ship is moving faster. This is why it is very important to have a ship with an aerodynamic shape. Mars The effect is negligible. A ship can ascend through the Martian atmosphere without any risk. Earth The Earth's atmosphere can slow down a ship. It is recommend for ships to fly vertically upwards for some distance before turning. Venus In case of Venus, it is recommended that, at least until you are 11 km above the atmosphere, to avoid ascending faster then 50 m/s. The Sun Given Sun's huge gravity, it is impossible to lift off. Bugs * Aerobraking does not occur when Time Warp is in progress. * Aerobraking does not occur after reloading a save(Version 1.4.06, tested on Android.) See Also *Advanced Orbital Mechanics *Deep Space Maneuvers *Gravity Assists *Oberth Effect *Trajectory Correction Maneuvers Category:Gameplay